My three daughters,all in their teens,have never had a cavity.My twins wore a brace for a few months,but it was mostly through vanity rather than necessity.
They are all slim as well.
Well I have no specific information about other European countries but as far as the UK is concerned I think it has more to do with Flouride in the water supply and in toothpastes,both of which I think were adopted significantly later than the USA,sometime in the 60s.
Having said that,my Dad is in his early seventies,has no teeth missing and just a few fillings.
On the downside,when I first started work in the city one of the female clerks was 21 yrs old and had dentures.That shocked me I can tell you.They didn't call her Evil Eve for nothing[xx(]